spratt



A 3 Sheets-Sheet l. C. SPRATT.

(No Model.)

SPEED INDICATOR.

e No. 568 046.

Patented Sept. 22,

-ff/IIS (No Model.) l3 Sheets-Sheet 2.

C. SPRATT. SPEED INDICATOR.

Patented sept. 22,1896.

loy

UNITED STATES' PATENT OFF-Ien,

y l-CIIARLES SPRATT, OFYLONDON, ENGLAND.

SPEED-INDICATOR.

SPECIFICATION forming part of Letters Patent No. 568,046, datedSeptember 2Q; 1896.

` Application nea December 23'-, 189s. stan sa; 573,102. or maar VTo allwhom it may concern,.-

Beit known that I, trician, a' subject of the Queen of Great Britain,residing at 9 Erlanger Road, New Cross Gate, London, in the c unty ofKent, England,

have invented a certain new and useful Speed is a specifi` Indicator, ofcation.

This invention relates to instruments whose action depends on magnetictorque, such as speed-indicators, ships logs, anemometers,trocheameters, or `anyother apparatus for the which the followingpurpose of indicating the speed of revolution of any rotating body. I

I have discovered that more accurate results are obtained by making theamature c of manganin or similar metal, insteadof the metals. (generallycopper) hitherto employed.

My improvements also relate-to lessening the .effects of friction insuch instruments and te making their indicators move inthe samedirection,'whether the driving-shaft revolv` ing forward or backward.

.the-dusk .with it;

manganin disk having -My speed-indicator iscOns'tructed inltheVfollowing manner: Fixed upon theshaft whose speed isto be indicated is awheel carrying on one side a number of magnets, which are preferablypermanent horseshoe magnets. Parallel to and coaxial with the wheel is.a its edge between the poles of the magnets, which point radiallyinward, 'or the edge of the disk may be turned inward and the magnetpoint outward. This disk can revolve about 'its axis, but in so doingwinds up a helical spring, one end of which' is fixed to itsv center,end is xcd to the frame of the machine. As the wheel revolves themagnets tend to carry but it only turns imi-il the tendency of themagnets to rotate it is exactly balanced by the resistance of thespring,

'and it then remains stationary so long as the speed of rotation of thewheel continues the The axis of the disk carries a hand or pointer whichrevolves overa properly-graduated scale, showing'thespeed of rotation ofthe wheel by the angley through which the disk has turned. Two helicalsprings are and their endsy are secured to the disk by being "simplypassed through slots in two pins fixed in the same face near to and oneon either side of its cen- CHARLES SPRATT, elec-- longitudinally.

l ing in one direction,

while the other of a speed-indicator constructed to' a square nut freeto move along the square end of the axle. By this meansavery'steady l5action is obtained and the reading off the inl-1 strument is littleaffected by-changes of tem perature, as any expansion or contraction ofthe springs only In orde` vto lessen the effect of friction on" themotion of the disk, I form' the bearing for' one end of. its spindle inthe shaft .-orx'wheel, so that this bearing. rotates while 'the other isfixed. The friction of one bearing there'- fore tends to acceleratethernotion ofthe disk and that of the: other t9 retard it, thesetendencies more o1' less counteracting each other.

When it is desiredto indicate the speed ofthe driving-shaft whenreversed, the fol- `lowing' device isl adopted: The wheel .,carrying themagnets' is not mounted upon thel causes, their ends tojniovejdrivi11g-shaft,l but on a separate shaft, at

whose end is fixed a bevel-pinion gearing with one 'or other 'oftwobevcl-wheels fixed on` a sleeve on the driving-shaft. This sleeve hasa diagonal slot in itwhichreceives apin fixed to the shaft. l/Vhen thedriving-shaft is movthe pingfis at one end of the slot and thecorresponding bevel-wheel is in gear; but when the motion is'reversedthe pin travels tothe; other end of the. slot, and the incline of the"tlatter causes the sleeve to move longitudinally on the shaft, throwingthe firstmentioned bevel-wheel out 4of gear and putting the other in,sothat'the ma'gnets are always'driven in the same' direction.

A light spring is provided bearing against the sleeve to prevent itsbeing turned by fric-- tien when the pin is traveling in the slot.

Figure 1 is a central longitudinal section according to this invention,`Fig. 2 is a transverse section on the line X X, Fig. 1, and Fig. 3 is aplan ofthe right-hand end of Fig. .1. Fig. 4 is a sectional, Fig.l 5 a1eft-hand, and Fig. 6 a right' hand, side elevation of adetail. Figs. 7and 8 show modifications of the springs.

a is the driving-pulley, and a' its shaft, to which the pin a2 is fixed.his pin works in au inclined slo`t in the sleeve b, whose ends carrybeveled pinions b b', one orother of which gears with the'pinions c onthe shaft c IOO f2 and Works in bearings g g.

(l are springs (omitted in Fig. 3) carrying friction-pads cl,bearing onthe sleeve L'. These prevent the sleeve h frombeing carried round merelyby the friction of the shaft a' and insure the pin ci by its actionon'the incline putting one or other of the pinions b' into gear with thepinion c. The shaft c' carriesa Wheel e, to which are fixed horseshoemagnets e','

preferably arranged, as shown, so that they alternately have their northand south poles next to the wheel. s

f is a disk of manganin, (an alloy of eightyfour per cent. copper,twelve per cent. man ganese, and four per cent. nickel being snitable.)lt is an advantage When constructing a 1ow-speed instrument to coat thenianganin disk with a thin deposit of copper, as it gives greatermagnetic torque and the temperature change only affects it slightly towhat it does a solid copper disk. The disk fis mounted on theshaftf',wl1ich carries a hand or pointer i The bearing g is fixed to theframe ofthe instrument and the bearing g to the shaft c'.

h h are two spiral springs, each having one end fixed to the shaft f' bybeing clipped between it and aplate h2, secured by a screw 7L, whiletheir other ends'are fixed to the bracket h4 on the frame of theinstrument by the screws h5.

The effective lengthot the spring 7L can be adjusted by a regulatorsimilar te that of a clock. 1t consists of an arm j, Figs. Il, 4f, and6, split at its end to embrace the spring and mounted on a plate j',which can be turned by apinj2,projeeting through a slot ja in the dial.k is a spring-arm against which the hand f2 strikes when it comes to thezero-point.

In place of the springs 7L h/ above described helical springs may beemployed, as shown at Figs. 7 and 8. One end of each is fixed to theframe, While the other ends are passed through slots'in two pins l onthe disk f, as shown in Fig. 7, or to a square nnt m on the end of theshaft f', which is squared to rcceive it, as shown in Fig. 8.

l. A speed-indicator comprising a shaft carrying a series of magnets,adapted to be connected with an object, the speed of which is to beindicated, a spindle carrying a disk in Uil proximity to said magnets,stationary bearings in which one end of the spindle is 1nounted, rotarybearings supporting the other end of the spindle7 and speed-indicatingdevices operated by the spindle,

2. A. speed-indicator comprising a spindle carrying a disk andindicating devices, a spring connecting the spindle with the frame ofthe instrumenha series of horseshoe mag- -fnets carried by a supportrotating near the disk, said magnets having their poles, one on eachside of the disk, the north poles of adjacent magnets being on oppositesides thereof, substantially as described.

3. The combination of a shaft driven from the part Whose speed is to beindicated, a disk seance fixed to a spindle free to rotate in bearings,one fixed and the other carried by the shaft, a spring having one endfixed te the spindle, the other to the frame of the machine, anindicator carried by the spindle and horseshoe magnets carried by theshaftembracing the disk and having their poles one on each side of it,the north poles of adjacent magnets being o'n opposite sides of thedisk.

4. The combination of a shaft driven from the part Whose speed is to beindicated, .a sleeve on the shaft, two beveled pinions fixed to thesleeve, an inclined slot in the sleeve, a pin fixed to the shaft andworking in the slot, a second shaft carrying a beveled pinion gearingwith one or other of -the pinions on the sleeve, friction-pads bearingon the sleeve to prevent it from being carried around by the friction ofthe shaft, a disk lixed to a spindle free to rotate in bearings, aspring having one end fixed to the spindle the other to the frame of themachine, an indicator carried bythe spindle and a magnet carried by theshaft and having one pole in proximity to the disk.

5. The combination of a shaft driven from the part whose speed is tobeindicatcd,a sleeve on the shaft, tWo beveled pinions .fixed to thesleeve, an inclined slot in the sleeve, a pin fixed-to the shaft andworking i n the slot, a second shaft carrying a beveled pinion gearingwith one or other of the pinions on the sleeve, a disk fixed to aspindle free to rotate in bearings, a spring having one end fixed to thespindle, the other to the frame of the machine, an indicator carriedbythe spindle and horseshoe magnets carried by the second shaftembracing the disk and having their polos one on each side of it.

il. 'lhe combination of a shaft driven 'from the part whose speed is tobe indicated,a sleeve on the shaft, two beveled pinions fixed to thesleeve, an inclined slot in the sleeve, a pin fixed to the shaft andWorking in the'slot, a second shaft carrying a beveled pinion gearingwith one or other of the pinons on the sleeve, a disk fixed to a spindlefree to rotate in bearings, a spring having one end fixed to the spindlethe other to the frame IOO of the machine, an indicator carried by thespindle and horseshoe magnets carried by the second shaft embracing thedisk and having their poles one on cach side of it, the north poles oi'adjacent magnets being "in opposite sides of the disk. v

7. The combination of a shaft driven from the part whose speed is to beindicated,a sleeve on the shaft, two beveled pinions fixed te thesleeve, an inclined slot in the sleeve, a pin fixed to the shaft andworking in the slot, a second shaft carrying abeveled pinion gearingwith one or other of the pinions on the sleeve, a disk fixed to aspindle free to rotate in bearings one fixed and the other carried bythe second shaft, a springhaving one end fixed tc the spindle the otherto the frame of the machine, an indicator carried bythe spindle ami:havingtheir b. The combination of a? slat't'dien'from 'the part whosespeed is to be indicated,a sleeve on the shaft, two beveled pinionsfixed to the A sleeve, an inclined slot'in the s1eeve, .a-pin fixed tothe shaft and working in-the slot, a

.second shaft carrying a, beveled pinion gearing with one or other ofthe pinions on the sleeve, a disk fixed to a spindle free to rotate Vinbearings, one-fixed-an the other carried 'by tbeseondshaft, a spring h"'ing `one enit fixed 'to the spindlmthe ether to the' frame f `themaehnef, an. indica-tor Veirriedby. the

spindle and horseshoe n'lagnets,I carried by the second shaftgmbraeingthe-disk and having l their poles one onf eaeh'side of it, the ixorth'.;

f pelesofadgaeentmagnets being .on opposite sides ofthe disk.v

' 1 CHARLES SPRATT. .Wit'nesses: jS. B. Similasan 'W. MORRIS.

